1. Field of the Invention
The present invention is directed to a method and apparatus for testing electronic components and particularly ceramic capacitors.
2. The Prior Art
In the manufacture of electronic devices, and particularly ceramic capacitors, a conventional final step in the processing thereof is subjecting the same to test conditions to determine whether or not the individual capacitors conform to prescribed specifications. Certain of the tests may be rapidly conducted, i.e. establishing that the capacitance of a given chip falls within a predetermined range. Tests of the noted sort are typically carried out by advancing the finished capacitors progressively past a testing station at which station the value of the chip may be instantaneously determined.
Where capacitors are to be employed in specialized environments, it may be necessary to subject the same to testing conditions over protracted periods. By way of example, it is frequently necessary to subject capacitors to heating conditions while continuously applying a voltage across the capacitors to determine whether short circuits would develop within the capacitor if used over extended periods in heated environments. Heretofore, such testing methods have necessarily involved complex testing devices. In one testing procedure often referred to as "burn-in" the chips are subjected to temperatures in the order of 100.degree. C. while being simultaneously subjected to a voltage equal to twice the voltage rating of the capacitor.
A method conventionally used for such testing involves mounting a multiplicity of the capacitors to be tested on a board or jig and applying the desired voltage simultaneously across the entire batch of capacitors to be tested or burned-in. Such a circuit has the obvious disadvantage that if a single unit or units evinced a short circuit, the applied voltage would be significantly drawn down, with the result that all of the other parts were improperly burned-in.
In an alternative burning-test method each capacitor is connected to the voltage source via a series connected fuse during the burn-in procedure. Since the fuses cannot withstand the heated environment to which the capacitors must be subjected, a complex multiple gang wiring arrangement is provided whereby the fuses are removed from the oven within which the capacitors are stored during testing and burn-in.
Since it is not uncommon to test several thousand parts simultaneously, the intricacy of the test apparatus will be readily apparent. Additionally, after each testing cycle, a further testing procedure must be effected to determine whether any of the fuses have opened, and to replace the specific fuses which are series connected to capacitors, which short during the burn-in procedure.
Although fuses have heretofore been developed which are susceptible of use in heated environments, no known method or apparatus is adapted to efficiently employ such fuses for a burn-in-testing procedure along the lines noted. Representative examples of fuse devices and/or testing methods of relevance may be found in the following U.S. Pat. Nos. 3,579,061; 3,236,976; 3,579,062; 3,638,083; 3,887,893; 4,107,759; 4,107,762; 4,193,106 and 4,296,398.